1. Field of the Invention
The invention relates to a hand brake device, more particularly to a hand brake device for a wheeled cart.
2. Description of the Related Art
Referring to FIG. 1, a conventional hand brake device 1 is shown to be mounted on a handle 2 of a wheeled cart, such as a stroller or a wheelchair (not shown) and comprises a housing 10, a brake lever 20, and a cable pull rod 30. The housing 10 includes a mounting portion 11 sleeved fixedly on the handle 2 of the wheeled cart, and a receiving portion 12 formed integrally with and disposed under the mounting portion 11. The brake lever 20 has a front end portion that is provided with a fixed positioning member 21 and that is disposed within the receiving portion 12 of the housing 10, and a lever portion 22 that extends rearwardly from the front end portion and that projects from the housing 10. The positioning member 21 has one end pivotally connected to the housing 10 by means of a first pivot pin 13, and the other end formed with upper and lower retaining portions 211, 212. The pull rod 30 is mounted in the receiving portion 12 of the housing 10, extends transverse to the brake lever 20, is disposed behind the positioning member 21 of the brake lever 20, and has an upper end pivotally connected to the housing 10 by means of a second pivot pin 14, a lower end connected fixedly to a brake cable 3, and an intermediate portion formed with an upper protrusion 31 and a lower protrusion 32.
In a normal operating condition of the cart, the upper and lower protrusions 31, 32 of the cable pull rod 30 are disposed between the upper and lower retaining portions 211, 212 of the positioning member 21 of the brake lever 20, and the lever portion 22 of the brake lever 20 extends parallel to the handle 2 of the cart.
Referring to FIG. 2, when the lever portion 22 of the brake lever 20 is turned toward the handle 2 of the cart, the lower retaining portion 212 of the positioning member 21 moves to abut against the lower protrusion 32 of the pull rod 30, thereby pushing the pull rod 30 to move rearwardly. The pull rod 30, in turn, pulls the brake cable 3 so as to result in a braking action on the cart. The hand brake device 1 is disposed at a first braking position at this time. When the lever portion 22 of the brake lever 20 is released, the restoring force of the brake cable 3 pulls the pull rod 30 and the lever portion 22 of the brake lever 20 to their original positions shown in FIG. 1, thereby restoring the cart to a normal operating condition.
Referring to FIG. 3, when the lever portion 22 of the brake lever 20 is turned away from the handle 2 of the cart, the upper retaining portion 211 of the positioning member 21 moves past the upper protrusion 31 of the pull rod 30, and is retained in a groove between the upper and lower protrusions 31, 32 of the pull rod 30 so as to push the pull rod 30 rearwardly. The pull rod 30, in turn, pulls the brake cable 3 so as to result in the braking action on the cart. The hand brake device 1 is disposed at a second braking position at this time. Even if the lever portion 22 of the brake lever 20 is released at this moment, the braking of the cart is still maintained until an external force is applied to the lever portion 22 of the brake lever 20, thereby restoring the pull rod 30 and the lever portion 22 to their original positions shown in FIG. 1, and thereby restoring the cart to its normal operating condition.
Although the conventional hand brake device 1 can achieve its intended purpose, however, in actual use, the conventional hand brake device 1 is found to have the following disadvantages:
1. Since the brake lever 20 and the pull rod 30 are connected pivotally to the housing 10 at two different positions by two independent pivot pins 13, 14 during assembly, elements of the hand brake device 1 are increased.
2. Referring to FIG. 4, although the lever portion 22 of the brake lever 20 can be turned to a large extent relative to the handle 2 of the cart, displacement (L) of the lower retaining portion 212 of the positioning member 21 of the brake lever 20 during braking of the cart is relatively small such that rearward displacement of the pull rod 30 and the brake cable 3 is not large, thereby reducing effectiveness of the hand brake device 1.
3. Since the first braking position of the hand brake device 1 is frequently applied to the cart, the lower retaining portion 212 of the positioning member 21 and the lower protrusion 32 of the pull rod 30 are easily susceptible to wearing.
Therefore, the object of the present invention is to provide a hand brake device that is capable of overcoming the aforementioned drawbacks of the prior art.
According to the present invention, a hand brake device is adapted to be mounted on a handle of a wheeled cart having a brake cable. The hand brake device comprises a housing, a brake lever, and a cable pull rod. The housing includes a mounting portion adapted to be sleeved fixedly on the handle, and a hollow receiving portion connected fixedly to and disposed under the mounting portion. The receiving portion includes a front wall, two opposite lateral walls extending integrally and rearwardly from the front wall, and a pivot pin fixed in the receiving portion. The front wall has an inner wall surface that is formed with a curved limiting groove, and a bottom portion that is formed with a through hole therethrough, which is adapted to permit extension of the brake cable into the receiving portion through the through hole. The brake lever includes a pivot connecting portion, a lever portion, and a positioning block. The pivot connecting portion is disposed within the receiving portion of the housing, and has a front lower portion formed with a rounded integral projection. The lever portion extends integrally and rearwardly from the pivot connecting portion, and projects from the housing. The positioning block is connected fixedly to the front lower portion of the pivot connecting portion. The rounded integral projection of the pivot connecting portion is received fittingly within the curved limiting groove in the front wall of the housing so as to permit rotation of the lever portion of the brake lever about the rounded integral projection in a direction away from the handle. The positioning block has an abutment surface and a retaining groove, which are disposed-above and behind the rounded integral projection of the pivot connecting portion and which define a rearwardly extending protrusion therebetween. The pivot connecting portion is formed with a curved slot unit that is disposed above and behind the rounded integral projection and that has a closed front end and a closed rear end. The pivot pin of the housing extends through the rear end of the curved slot unit such that the brake lever can be turned upwardly and downwardly, thereby moving the lever portion toward and away from the handle. The cable pull rod is disposed within the receiving portion of the housing, and is located behind and abuts against the positioning block. The cable pull rod has a top end sleeved rotatably on the pivot pin of the housing, a lower end adapted to be connected fixedly to and pulled forwardly by an end of the brake cable, and a retaining portion for engaging the retaining groove in the positioning block. When the lever portion of the brake lever is turned upwardly, engagement between the retaining portion of the cable pull rod and the retaining groove and location of the pivot pin within the rear end of the curved slot unit are maintained such that the positioning block pushes the cable pull rod to turn rearwardly so as to rotate the brake lever about the pivot pin, thereby moving the rear end of the brake cable rearwardly for braking the cart, after which, upon release of the lever portion of the brake lever, the brake cable pulls and moves the lower end of the cable pull rod forwardly to engage the rounded integral projection of the brake lever within the curved limiting groove in the front wall of the housing. When the lever portion of the brake lever is turned downwardly, the lever portion of the brake lever rotates about the rounded integral projection of the pivot connecting portion such that the pivot pin slides from the rear end of the curved slot unit to the front end of the curved slot unit so that the retaining portion of the cable pull rod separates from the retaining groove in the positioning block to move past the rearwardly extending protrusion of the positioning block so as to engage the abutment surface of the positioning block, thereby pulling and moving the rear end of the brake cable rearwardly for braking the cart and thereby preventing further rotation of the brake lever about the rounded integral projection, after which the brake lever can be turned upwardly toward the handle only when an external force is applied to the lever portion of the brake lever.